Dry spinning apparatus



Jan. 2, 1945. .1. R. McCOMB DRY SPINNING APPARATUS Filed April 9, 1943 IN V EN TOR.

James Robert M Comb Patented Jan. 2, 1945' UNITED STATES r PATENT OFFICE v 2.300.275 I DRY srmnmq APPARATUS James RobertMcComb; Waynesboro, Va, aaaignor to E. I. du Pont de Nemours'dz Company, Wilmlngton, Del., a corporation of Delaware Application April 9, 1943, Serial No. 482,447

3 Claims. (01. 18-8) method. These difllculties, chief of which are frequent breakage of the primary filaments, too

' great a proportion of stuck filaments, and poor spinningcontinuity, increase in intensity as the speed of spinning is increased and the indications are that they are occasioned primarily by faulty or ineflicient removal of solvent from the filament bundle in the first few inches of travel from the spinneret and/or improper flow of evaporative medium through the cell. However, the usual expedients heretofore successfully employed for initially securing uniform and efficient solvent removal from smaller filament bune dies and for securing proper flow of the evaporative medium through the 'cell' do not serve to overcome the defects encountered in the dry spinning of heavy denier yarns.

An object of this invention therefore is to provide in dry spinning apparatus novel means for introducing therein evaporative medium in such manner that large denier yarns can be satisfactorily and continuously spun at relatively high speeds. The above-and other objects will more clearly appear hereinafter.

I have found that if solvent-free evaporative medium is introduced into the cell through identical tubes which terminate at opposite sides of the filament bundle in the immediate vicinity of the spinneret and at equidistant points which may vary from about 0.75 to about 2 inches from the vertical center line of the filament bundle at the spinneret; and if, in addition, a reticular obstruction sufficient to reduce theeffective area of the opening at the outer end of one tube from to is placed over said opening of one tube, the flow of evaporative medium about the filaments and through the cell is such as to substantially eliminate filament breakage, stuck filament, and to permit a uniformly continuous production of heavy denier yarns at a relatively high rate of speed.

The details of my invention will now be described with reference to the accompanying drawing wherein like reference numerals indicate like parts, and wherein Figure I is a front elevation of the head of a spinning cell with parts of the spinning cell broken away to show the disposition of the openings or passages according to a preferred modification of my invention.

Figure II is a side elevation of the device of Figure I.

Figure III is an alternative form of passage.

Referring to Figure I, the head of the spinning cell comprises a box-like enclosure linto which extends a spinning solution supply line 2 which terminates within the cell in a spinneret 3 adapted to spin filament bundles of at least 500 denier. Air (or equivalent evaporative medium) inlet tubes 4 and 5, which in the preferred embodiment of my invention are cylindrical in form, project into cell I from opposite side walls thereof substantially in line with the plane of the spinneret face, and to within about one inch of the vertical line of the filament bundle at the spinneret. Tubes 4 and 5 are of the same diameter, which is preferably about 2.5 inches but which should not be less than 2 or more than 3 inches.

The outer end of tube 6 is covered by a reticulate structure or screen 8 of any desired material. Preferably screen 8 consists of a coarsely woven, knitted or matted cloth such as cheesecloth, netting, gauze, or the like. From the standpoint of economy and ready adaptability, cotton textile fabrics are preferred. However, uniformly constructed fabrics of wool, silk, viscose rayon, cellulose acetate, linen, nylon, etc.,

and uniform reticulate screens of metal, plastics, wood, fiber, etc., may also be effectively employed. It is essential, however, that the structure used be so formed that the interstices thereof constitute from to 85%, and. preferably from to of the total area, whereby from 65% to and preferably from'70% to 80%, of the area of opening 5 is left for the free passage of air or other solvent-free evaporative medium into the cell.

Any suitable expedient for mounting or attaching the structure 6 on tube 5 may, of course,

be employed.

An alternative form of tube is illustrated in Figure III. Here, the tube is frusto-conical in form with the smaller end projecting into the spinning cell. Tubes of any other cross-section, e. g., rectangular, elliptical, triangular, etc., may likewise be used in place of the cylindrical tubes of Figs. I and II. However, whatever form of tube is used, it is essential that the cross-sectional area of the open end thereof in the cell be not less than the area of a circle of about 2 inches in diameter (about 3 square inches), or more than the area of a circle of about 3 inches in diameter (about 7 square inches).

While my invention is adapted particularly to dry spinning of cellulose acetate solutions, it is also equally as useful in the production of heavy denier yarns of any organic solvent-soluble filament-forming substance by the dry or evaporative method of spinning.

The improved apparatus of my invention makes possible for the first time the continuous dry spinning from a single spinning position of filament bundles of from 500 to 1000 denier, consisting of filaments of cellulose acetate or the like-having a filament size of from 2 to denier, I

with relatively few breaks, a minimum of stuck filaments, and at speeds of from 200 up to 500 yards per minute and over.

It is to be understood, of course, that the improvement hereinabove specifically described is susceptible to many obvious changes and modifications without departing from the spirit or scope of my invention as defined in the following vertical center line of the filament bundle at the spinneret, one only of said tubes having its outer openin covered by a substantially uniformly reticulated structure the interstices of which amount to not less than 65% and not more than 85% of the area of the structure whereby the varea. of said outer opening is reduced at least 15% and not more than 35%.

2. In dry spinningapparatus comprising a spinning cell and a spinneret therein adapted for spinning filament bundles of from 500 to 1000 denier, the improvement which comprises two open-ended, oppositely disposed cylindrical tubes of the same diameter within the range of from about 2 to about 3 inches, extending into said cell in close proximity to the spinneret and terminating at equidistant points not less than 0.75 and not more than 2 inches to either side of the vertical center line of the filament bundle at the spinneret, one only .of said tubes having its outer opening covered by a textile fabric the interstices between the threads of which amount to not less than and not more'than of the area of the fabric whereby the area of said outer'oponing is reduced at least 15% and not more than 35%.

\ 3. In dry spinning apparatus comprising a spinning cell and a spinneret therein adapted for spinning filament bundles of from 500 to 1000 denier, the improvement which comprises two open-ended, oppositely disposed, cylindrical tubes of the same diameter within the range of from about 2 to about 3'inches, extending into said cell in close proximity to the spinneret and terminating at equidistant points about one inch to either side of the vertical center line of the filament bundle at the spinneret; one only or said tubes having its outer end covered with a layer of cheesecloth the interstices between the threads of which amount to not less than 65% and not more than 85% of the area of the layer of cheesecloth whereby the area of said outer opening is reduced at least 15% and not more than 35%.

JAMES ROBERT McCOMB. 

